Histopathologic evaluation of response to treatment of human tumors implanted under the renal capsule of normal immunocompetent mice.

The histopathologic changes following chemotherapy treatment of fresh human tumors implanted under the renal capsule of normal immunocompetent mice were evaluated. On the basis of the histopathologic profile of the xenografts, four parameters were recognized: (1) cancer area (C), (2) necrosis area (N) (each measured by image analysis), (3) pathologic effect of cancer cells (P) (assessed histopathologically), and (4) number of mitoses (M) (counted microscopically), and were scored in a semiquantitative fashion from 0 to 2 or 4. The drug sensitivity (S) was scored using the following formula: S = C + P + M - N; this score varied from -4 to 10. Histopathologic changes represent a sensitive indicator of the response of implanted human tumors under the renal capsule to anticancer drugs. Availability and correct interpretation of the post-treatment histopathologic picture is of importance in selecting the proper combination treatment which would maximize tumor response.